1. Field of the Invention
The present invention relates to a bending apparatus in which, by performing a tilt operation that changes a tilt direction and a tilt angle of an operation element provided in an operation portion, it is possible to move a pulling member and effect a bending operation of a bending portion provided in an insertion portion.
2. Description of the Related Art
In recent years, endoscopes that include an elongated insertion portion are being utilized in a medical field and an industrial field. Endoscopes utilized in the medical field are used to perform observation and the like by inserting the insertion portion into a body from an oral cavity or an anus or the like. Further, with an endoscope used in the industrial field, an observation can be conducted by inserting the insertion portion into a pipe of a boiler or inside an engine or the like.
In an endoscope, generally, in order to be able to point an observation optical system provided in a distal end portion of the insertion portion in a desired direction, a bending portion that bends, for example, in the vertical and lateral directions is provided on a distal end side of the insertion portion. A bending knob for effecting a bending operation of the bending portion is pivotably arranged in an operation portion that is provided at a proximal end of the insertion portion. An angle wire is connected at a predetermined position of the bending portion and at a predetermined position of the bending operation knob. In an endoscope configured in this manner, the configuration is such that when an operator rotates the bending operation knob clockwise or counterclockwise using fingers of a hand that is grasping the operation portion, the angle wire is pulled or slackened and the bending portion bends. (Hereunder, an endoscope having this configuration is referred to as a “conventional endoscope.”)
In recent years, endoscopes have been proposed which have driving means that is provided inside an operation portion of the endoscope, and in which a bending operation of a bending portion can be effected by operating an operation element that is a bending mechanism with a single finger. For example, in FIG. 6 in Japanese Patent Application Laid-Open Publication No. 08-224241, an endoscope is illustrated in which a bending pipe is bent vertically and laterally by operating a joystick that is an operation element provided in a casing. According to this endoscope, when a surgeon subjects the joystick to a tilt operation, a controller converts the tilt operation into a bending angle in a vertical or lateral direction, and drives a driving actuator for vertical bending and/or a driving actuator for lateral bending. Thereupon, a wire is pulled/slackened by the driving force of the actuator and the bending portion performs a bending operation. Therefore, the surgeon can easily adjust the bending portion of the distal end portion.
However, in an endoscope in which a wire is pulled by a driving actuator, the wire is not directly pulled by the joystick that the surgeon operates. Consequently, a change does not occur in the operability of the joystick even if, during a bending operation of the bending portion, for example, the distal end portion contacts against living tissue and a load that is applied to the wire increases.
Japanese Patent Application Laid-Open Publication No. 2003-325437 discloses an endoscope that is equipped with a pulling member operation apparatus with which it is possible to effect a bending operation of a bending portion by tilting an operation instruction lever as an operation element using a slight amount of operation force thereby to directly move a desired pulling member by a desired amount. In this endoscope, by tilting a bending lever thereby to change a tension state of an operation wire that corresponds to the tilt operation direction that is fixed to an arm member, a drag between the operation wire and a pulley that is being rotated by a motor is changed. Thereupon, the operation wire is moved in the direction of rotation of the pulley and the bending portion bends. According to this endoscope, the relevant wire is directly pulled when a tilt operation of the bending lever is performed. As a result, operability is obtained such that, for example, when the distal end portion contacts against living tissue during a bending operation, the amount of tilt operation force increases along with an increase in a load that is applied to the relevant wire, and thus the above described problem can be solved.
In addition, Japanese Patent Application Laid-Open Publication No. 2010-207598 discloses an endoscope equipped with the pulling member operation apparatus described in Japanese Patent Application Laid-Open Publication No. 2003-325437. An operation portion of this endoscope includes an operation portion body, and a grasping portion that is provided on a side opposite to an insertion portion of the operation portion body so that an axis direction intersects with an insertion axis of the insertion portion and inclines downward relative to the insertion axis. When the grasping portion is grasped with the little finger, the ring finger, and the middle finger, a bending operation lever of this endoscope protrudes from a middle position on a front surface side of the operation portion body that is a position at which an operation can be performed with the thumb. Further, in this endoscope, a plurality of operation switches are disposed on a front surface side of the operation portion body on the grasping portion side that is in the vicinity of the bending operation lever.